The Contribution of Small Impact Craters to Lunar Polar Wander
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Date
2022-09-19
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Citation of Original Publication
Smith, David E. et al. "The Contribution of Small Impact Craters to Lunar Polar Wander." The Planetary Science Journal 3, no. 9 (19 September 2022). https://doi.org/10.3847/PSJ/ac8c39
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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract
Changes in mass distribution affect the gravitational figure and reorient a planetary body’s surface with respect to
its rotational axis. The mass anomalies in the present-day lunar gravity field can reveal how the figure and pole
position have evolved over the Moon’s history. By examining sequentially each individual crater and basin,
working backward in time order through the catalog of nearly 5200 craters and basins between 1200 and 20 km in
diameter, we investigate their contribution to the lunar gravitational figure and reconstruct the evolution of the pole
position by extracting their gravitational signatures from the present-day Moon. We find that craters and basins in
this diameter range, which excludes South Pole–Aitken, have contributed to nearly 25% of the present-day power
from the Moon’s degree-2 gravitational figure and resulted in a total displacement of the Moon’s pole by ∼10°
along the Earth–Moon tidal axis over the past ∼4.25 billion years. This also implies that the geographical location
of the Moon’s rotational pole has not moved since ∼3.8 Ga by more than ∼2° in latitude owing to impacts, and
this has implications for the long-term stability of volatiles in the polar regions